Transcript Community Ecology

Chapter 54
Community Ecology
Community Ecology
• The study of the interactions
between the species in an
area.
Interspecific Interactions
• Interaction between species.
• May be positive, negative, or
neutral (in regards to fitness)
• Ex:
Predation
Mimicry
Competition
Symbiosis
Predation (+/-)
• Predator and
prey
relationships.
• Ex – Lynx and
Hares
Herbivory (+/-)
• When an organism eats parts
of a plant or algae.
• Herbivore – may have special
adaptations to find their prey.
• Plants – may have
adaptations to avoid being
eaten.
Predation/Herbivory
• Often results in interesting
defenses or adaptations.
• Ex:
• Cryptic coloration
• Aposematic coloration
Cryptic Coloration
• A passive defense where the
prey is camouflaged against
its environment.
Aposematic Coloration
• The use of
conspicuous
colors in toxic
or unpalatable
organisms to
warn off
predators.
poison arrow frogs
Mimicry
• Defense mechanism where the
mimic has a resemblance to
another species, the model.
• Types:
• Batesian
• Müllerian
Batesian Mimicry
• Palatable species mimics an
unpalatable model.
Hawk moth larva
Snake
Müllerian Mimicry
• Two unpalatable species
resemble each other.
Cuckoo Bee
Yellow Jacket
Competition
• When two species rely on the
same limiting resource.
• Intraspecific competition
usually more severe than
Interspecific competition.
• Why?
Competitive Exclusion
Principle
• Predicts that two species with
the same exact requirement
cannot co-exist in the same
community.
• The better adapted species will
survive and the less adapted
will go extinct.
Think, Pair, Share
• Discuss if the Competitive
Exclusion Principle explain the
spacing of fast food
restaurants on the “strip” in
most towns.
Ecological Niche
• The sum of a species’ use of
the biotic and abiotic
resources in its environment
is called the species’
ecological niche.
• How a species “makes its
living” in its ecosystem.
• Species can not have niche
overlap, the Competitive
Exclusion Principle
Niche Types
1. Fundamental - what a species
is theoretically capable of
using.
2. Realized - what a species can
actually use.
Think, Pair, Share
• Again in terms of fast food
restaurants, explain the
concept of a fundamental vs.
realized niche.
Resource Partitioning
• A way that species avoid niche
overlap by splitting up the
available resources.
• Ex: Anolis lizards
A. distichus
A. insolitus
Symbiosis
• When two different species
live together in direct contact.
• Types:
1. Parasitism
2. Commensalism
3. Mutualism
Parasitism (+/-)
• Parasite harms the host.
• Parasites may be external or
internal.
• Well adapted parasites don't
kill the host.
• https://www.youtube.com/watc
h?v=uvdiYg6ZN-U Sci-Show
Parasites
Commensalism (+/o)
• One partner
benefits while
the other is
unchanged.
• Ex. – Cattle and
Egrets
Mutualism (+/+)
• Both partners
Acacia Tree and Ants
benefit from
the
interaction.
• Ex:
Pollinators
and flowers
Species with large impacts
• Some species have larger
impacts on a community
structure than others.
• Ex:
• Dominant Species
• Keystone Species
• Foundation Species
Dominant Species
• A species that is the most
abundant or has the highest
biomass in a community.
• Has a major effect on a
community both biotically and
abiotically.
Reason for Dominance?
• Best Competitor?
• Best in avoiding predators and
disease?
• Invasive species may fit the
last explanation.
Example
• Chestnuts – used to make up
to 40% of the forest.
• Lost between 1910-1950
because of fungus disease.
• Major impact on wood and nut
industries.
Response
• Some tree species increased
in abundance to fill the gap.
• Mammals and birds did OK.
• 7 species of insects went
extinct.
Keystone Species
• Not a dominant species,
but has a major impact in
the community structure.
• Often a top predator that
controls the numbers of
other species.
• Ex. Sea Otters
Foundation Species
• Species that cause physical
changes in the environment
that affect others.
• Ex. Beavers, Bison, Black
Rush
• https://www.youtube.com/watc
h?v=ysa5OBhXz-Q
• How wolves change rivers
Succession
• Changes in
species
composition
over time.
Succession Stages
• Climax Community -
An ecological community in w
hich populations of plants or
animals remain
stable and exist in balance
with each other and their envi
ronment.
Succession Types
1. Primary
2. Secondary
Primary Succession
• Succession with only abiotic
materials as the starting
substrate
• Ex: volcanic islands
glaciated areas
road cuts
Secondary Succession
• Succession with biotic
materials (living or dead) as
the starting substrate
• Ex:
• Cutting down a forest
• Forest fire
• Tornado/storm damage
Steps of Succession
• Pioneer Species – the first
organisms to appear in the
area in primary succession
• Usually moss or lichens
What do Pioneer Species
Change?
• Enrich the soil – as
generations die, their remains
decompose and add nutrients
to the soil (often N).
• The soil is now able to support
a greater variety of species
such as grasses and small
shrubs.
• Which occurs faster, primary
or secondary succession?
• What can you do to speed up
succession?
Point
• If you understand the causes
and controlling factors of
succession, you can
manipulate them.
Some points about
Succession
• The Organisms are changing
in the area over time. General
pattern is an increase in
biodiversity.
• The Climate of the area is NOT
changing over time.
Other Changes
• Soil – becomes richer in N,
more depth, better water
retention etc.
• Light – can decrease at ground
level because of shading by
taller plants.
Summary
• Know the various types of
interspecific interactions.
• Know the Competitive
Exclusion Principle and Niche
Concept.
• Know Species with large
impacts.
Summary
• Know some examples and
causes of succession.